Presolvated aluminum soap gelling agents



' PRESOLVATED ALUMINUM SOAP GELLING AGENTS E. Van Strien, Grifiith, Ind., assignor to Standard .011 Company, Chicago, 11]., a corporation of Indiana No Drawing. Application December 30, 1953,

Serial No. 401,397

Claims. (01. 252-316) This invention relates to improvements in the preparation and use of bodying agents for liquid hydrocarbons. More particularly, the invention pertains to improved gelling agents capable of gelling liquid hydrocarbons at a rapid gelation rate to obtain stable gels for use as military incendiaries.

. Specifically, the invention is directed to the preparation and use of a bodying agent adapted to form, at relatively low bodying agent concentration, stable gels of relatively high consistency with a wide boiling range of petroleum gasolines, jet fuels, diesel fuels and kerosenes, preferably liquid hydrocarbons boiling within the range. of from about 100 to'600 F. Such solidified or gelled liquids are useful as charges for incendiary bombs, grenades, flame throwers, and the like.

.Exactingrequirements for military incendiary gelling agents have been established. Hydrocarbon gels made therefrom must be stable at temperatures over the range of from about-40 to +65 C., so that they may be used in any climate. They must not be susceptible to premature breakdown With loss of viscosity. They must adhere to a target sufficiently long to set it on fire. They must be capable of easy ignition even at subzero temperatures. In addition, it is highly desirable that the gelling agent be capable of forming gels which meet these requirements with a wide variety of hydrocarbon fuels at a rapid rate'of gelation and at the lowest possible concentration for purpose of economy of material as well as economyof time and storage space necessarily limited under Wartime conditions. In general, most gelling agents for hydrocarbon fuels have not met all of the above re:

2,751,360 Patented June 19, 1956 viscosity of from about 100 seconds to 1500 seconds at 100 F; (Saybolt Universal) and initial boiling point above about 575 F. Light hydrocarbon oils are not suitable as presolvating oils. a viscosity of about 50 seconds at 100 F. (Saybolt Universal) when used to presolvate aluminum isooctanoate gelling agent failed to improve the gelation rate of a synthetic gasoline. This failure may have been due to the low boiling range of the mineral seal oil which was from about 500 F. to about 700 F. at atmospheric pressure'.' The sorbed hydrocarbonoils should be of higher average molecular weight than the liquid hydrocarbons to be gelled by my improved gelling agent. I have discovered that the'sorbtion of the heavy hydrocarbon oils in amounts within the range of about 2.0 percent to about 25 percent, preferably from about 5 percent to about 15 percent, by weight based on the acid equivalent of the basic aluminum octanoate .soap, in-' weight of the 'octanoic creasesvery substantially the gelation rate of liquid hydrocarb'ons, particularly when the basic aluminum octanoate gelling :agent is used at concentrations below:

about 6 percent, if the sorbtion of the oil is concomitant p The reaction product is fractionated to obtain a fraction quirements. Gelling agents vvhich have the property of,

imparting highrates of gelation to liquid hydrocarbons at relatively low concentrations in hydrocarbon media' usually form very unstable gels which break downprematurely. On the other hand, gelling agents which form stable, moisture resistant gelled hydrocarbons usually have been incapable ,of providing the rapid gelling rates re q'uired t o meet the exigencies of wartime use thereof.

A primary object of this invention is to provide a gel-ling agent which is effective in small amounts for the gellingot petroleum gasolines, aviation gasoline, kerosene, diesel fuels, and jet fuels at ambient temperatures to form stable gels suitable for use as military incendiaries. An other object of the invention is to gel hydrocarbons at relatively low concentrations and at relatively rapid gelling rates to gels having suitable viscosity, which suitable -viscosity is maintained upon aging under variable at-- tary uses. An additional object is to provide a gelling agent having a gelling rate which isrelativelyinsensitive to temperature. Further objects will appear from the'dewith the precipitation of the basic aluminum octanoate.

sorbant.

Briefly, volvesa. step of the process, the production of. branched chain heptenes by reacting a hydrocarbon stream containing a mixture of propylene and butylenes in the presence of an acid type catalyst such -as supported phosphoric acid.

the preparation of my preferred gelling agent inconsisting essentially of a mixture of branched chain heptenes which are reacted in a second conversion stage with hydrogen and carbon monoxide in the presence of a cobalt-containing catalyst to produce a mixture of isooctyl aldehydes, i. e., by the Well-known oxo process. The

isooctyl aldehyde product is fractionated to obtain a Ca aldehyde-Cs alcohol fraction which is then hydrogenated in the presence of acobalt or nickel catalyst to-obtain an isooctyl alcohol product which product may be fractionated to remove therefrom substantially all components higher boilingand lower boiling than isooctyl alcohols. The isooctyl alcohol fraction is converted to the alkali metal soap of 'the'co'rresponding acids by fusion with an alkali metal hydroxide.

In preparing my improved gellingagent an aqueous solution of the alkali metal soap, such as sodium isooctanoate soap, and containing-sufiicient free alkali metal hydroxide, i. e., sodium hydroxide, to form basic aluminum isooctanoates, defined hereinbelow, when contacted with an aqueous solution of an inorganic aluminum salt,

such as an aqueous solution of aluminum chloride, is

agitated in the presence of a lubricating type petroleum oil to produce an emulsion 'of the oil in the basic solution of sodium isooctanoate. The aqueous solution of the aluminum salt is then added to the emulsion to produce concomitant precipitation of the branched chain basic to emulsification of the oil therein, thus providing 2-ethylhexanoate radicals in the improved gelling agent. I also tailed'description of the illustrative embodiments of the;

invention set out hereinafter.

My preferred gelling agent consists of a mixture of isomeric basic aluminum octanoate soaps, defined hereinbelow, in close association with sol-bed hydrocarbon o ls, H of lubricating oil viscosity and boiling range,- that is,"

ment of gelation time of such soap.

aluminum isooctanoate and sorbtion-of-theoil therewith. If desired 2-ethylhexanoic acid or an aqueous solution of an alkali metal soap of Z-ethylhexanoic acid may be added to the aqueous solution of alkali metal isooctanoate prior have discovered that sorbtion of the oil by basic alumi num Z-ethylhexanoate per se from an'emulsion of the oil in an aqueous solution of alkali metal. 2 -ethyll 1exanoate improves the gelation rate of the 2-ethylhexanoate ge1l-' ing agent. Presolvation of soap containing Z-ethylhexanoate radicals and issoctanoate radicals. with heavy hydrocarbon oils defined above results in marked improve- The precipitated soaps are washed free of inorganic salts Thus a mineral seal oil having series of reactions which includes as aninitial and dried, preferably in two steps with an intermediate comminuting step such as grinding. If desired the comminuting step may be carried out in the presence of a small amount of silica aerogel anti-agglomerant or separating agent, that is from about 1.0 percent to about percent based on the weight of soap, to facilitate reduction of the product to a powder and to prevent agglomeration of the finished soap in storage.

More specifically, my improved gelling agents are pro duced by precipitating branched chain basic aluminum octanoates from basic aqueous solutions of branched chain alkali metal octanoates, said aqueous solutions hav-v ns emuls d h re n a solvating hyd oc rbon oil n moun s fil ent to Pro id rom bou 2. perc nt to about 5 P c nt of a d o based n th cetan ic a id n nt o e soap- In produc ng h heptene Po ymer Prim ry n erme ia e to obtain the isooctanoate component of my improved gelling agent the feed to the polymerization reactor contains from about 30 percent to about 60 percent mixed propylene and butylenes. The mol ratio of propylene to total C3; and C4: olefins may be varied from about 0.2 to 0.65 with optimum yields of heptenes being obtained at mol ratios of 0.3 to 0.4. It was found that the composition of the branched heptenes did. not change appreciably when operating conditions were varied with? in these ranges. A typical polymer, obtained by polymerizing a C3; plus Ci stream at a temperature of 385' F., and a pressure of 1200 pounds per square inch in the presence of phosphoric acid catalyst at a conversion of 93 percent, was found to contain in the rough heptene cut, 1 percent hexenes, 89 percent branched chain heptenes, and percent octenes. The analysis of the heptene fraction obtained by the refractionation of the rough cut is shown in Table l, the analysis being based on temperature and refractive index relations of the various fractions. The heptene cut obtained upon refractionation was used as feed to the oxo process described below.

ABL 1 Olefin composition: C7 oxoation feed oxoation process to obtain branched chain Cs aldehydes and Ca alcohols for use in obtaining the isooctanoate component of my improved gelling agent. Furthermore, not more than 25 percent to 30 percent of the possible 1.0 percent normal heptenes would oxoate to produce 2-ethylhexylaldehyde which upon hydrogenation would produce 2-ethylhexanol. Thus there is less than about 0.3 percent Z-ethylhexanoic acid in the isooctanoic acid produced from the heptene polymer intermediate.

The mixed or copolymers (branched heptenes) are subjected to the so-called oxo reaction. An equimolar gaseous mixture of hydrogen and carbon monoxide together with the C1 polymer are contacted in the presence of a cobalt-containing catalyst at temperatures within the range of 300 F. to 400 F., for example 350 F., and at a pressure of about 3000 p. s. i. g. Contact with the catalyst is made at a liquid space velocity within the range of about 0.3 to about 3.0 volumes of liquid per The mol ratio of saturated hydrocarbons and a small amount of heavypolymer. The total reaction product is steam stripped and fractionated to produce a mixture of C5 alcohols which is essentially free of heavy polymer and which contains only small amounts of non-oxoated hydrocarbon material.

The purified oxo product is hydrogenated in the presence of a catalyst such as nickel, cobalt or copper chromite under conditions to selectively reduce the branched Cs aldehydes of the oxo product mixture to the corresponding branched Cs alcohols without appreciable reductiou. of the alcohols to hydrocarbons. For example, the hydrogenation may be carried out at temperaturesin h range of, about 350 F. to about 500 F., and pressures of 30 to 300 atmospheres in the presence of cobalt catalyst to convert the aldehydes to alcohols. The product is fractionated to obtain a Ca product consisting essentially of branched; chain isomeric octyl alcohols which, for purpose of this specification and claims, I designate as isooctyl alcohol.

The Purified isooctyl alcohol is converted directly to he a kali, metal soaps of the isooctanoic acids corre sQQuding-to the mixed isomeric octyl alcohols in the isooetyl alcohol by heatingan intimate mixture of the isooctyl alcoholwith an alkali metal hydroxide, for example, sodium hydroxide, at temperatures in the range of about 600- F.-725 F. The basic aluminum isooctanoate soap;

metal soap may be carried out in the presence of. the.

inert heavy hydrocarbon oil to be sorbed, such as white oil. Water is added to the organic acid-caustic alkali:

product and the aluminum soap containing the sorbed oil isprecipitated therefrom by adding the aqueous solutionof aluminum salt such as aluminum chloride.

The composition of purified isooctyl alcohols derived fromtheCq copolymer feed of Table 1' was determined by employing the analytical techniques of fractionation,

refiactometr'y and infrared spectral analysis of the corresponding octenes derived by dehydration of the purified isooctyl alcohol. Based upon these studies, the estimated composition of the purified isooctyl alcohol is shown in Table 2. a

TABLE 2 Estimated composition of isooctyl alcohol Isomer: Probable range, percent 3,4-dimethylhexanol 20-30 4,5-dimethylhexanol 15-25 3,5-dimethylhexanol 10-1 5 4-methylheptanol 10-15 S-methylheptanol 510 S-methylheptanol 5-10 4-ethylhexanol 5-10 6-methylheptanol 5-10 3-ethyl-4-methylpentanol 5-10 2,4-dimethylhexanol 0-5 2,5-dimethylhexanol 0-5 2-ethyl-4-methylpentanol 0-5 4,4-dimethylhexanol 0-5 5,5-dimethylhexanol 0-5 Certain C8 alcohol isomers, which are theoretically possible based on the composition of the olefin feed shown in Table l, were not found in the purified isooctyl alcohol. These isomers may have been lost by fractionation of the isooctyl alcohol. On the other hand, the C7 olefin precursors of the missing alcohol isomers probably are converted to other C7 olefin isomers in the oxo reaction by shift of the ethylenic linkage. Thus, for example, no evidence of isopropyl substituent groups in the purified oxo alcohols was found although oxoation of Z-methylhexene-3 should produce, by oxoation and hydrogenation, 2-isopropylpentanol along with 2-ethyl-4-methylpentanol. Likewise, oxoation of 2-methylhexene-2 followed by hydrogenation should yield 2-isopropylpentanol exclusively in the absence of ethylenic linkage isomerization. In like manner oxoation of 2,4-dimethylpentene-2 followed by hydrogenation of the oxoated product should yield 2-isopropyl-3-methylbutanol'but with shift of the ethylenic linkage to the 1-position the alcohol product would be 3,5-dimethylhexanol. This branched chain alcohol is present in considerable quantity in the purified Ca alcohol mixture. Other evidence supports the conclusion that there is extensive isomerization of ethylenic linkage of the olefins in the oxo reaction. For example, it was found that the 247 parts of 2,3-dimethylpentene-2 per 1000 parts of the mixed isomeric C7 olefins of Table 1 are reduced to only 16 parts by successive passes through the oxo reaction zone, a reduction of about 93 percent. A substantially pure 2,3-dimethylpentene-2 responds to oxoation to the extent of about 70 percent, indicating that according to the accepted theory an ethylenic linkage joining two tertiary carbon atoms will respond to oxoation it, in such oxoation process the ethylenic linkage shifts to a more favorable position. Therefore, a shift of the ethylenic linkage of 2,3-dimethylpentene-2 to the 1-position would produce, by oxoation and reduction, 3,4- dimethylhexanol. It is believed that such shift accounts for a major part of the relatively large amount of 3,4- dimethylhexanol in the purified C's alcohol fraction. On the other hand, isomerization of alkyl substituent groups per se in the mixture of isomeric heptenes, which isomerization would result in the alteration of the carbon to carbon structure of the alkyl groups, does not take place in the oxoation stage or in any other stage of the process to which the heptenes and intermediates derived therefrom are subjected in producing the isooctanoate component of my novel gelling agent.

There is less than about. 0.3 percent of 2-ethylhexyl alcohol in the purified oxo alcohols. The presence of less than about 0.3 percent of 2-ethylhexyl alcohol in the isooctyl mixture is explained on the basis that this octyl alcohol is derived from only normal straight heptenes and, as stated above, tains less than about and the isooctanols contain less than about 0.3 percent 2-ethylhexanol.

Examination of Table 2 indicates that at least percent of the total isomeric C3 alcohols in the purified oxo alcohol are methyl substituted of which at least 50 percent are dimethyl hexanols and not more than 25 percent of the Ca alcohols are ethyl substituted, and the Ca alcohols contain less than about 0.3 percent 2-ethylhexanol. Thus, for purpose of definition in this specification and the claims supported thereby, I use the term isooctanoate to designate the product consisting of mixed branched chain isomeric octanoates which are derived from the isomeric octyl alcohols, that is, the purified Ca alcohol fraction, and the isooctanoate is defined as a soap of isomeric branched chain octanoic acids which acids are at least 90 percent methyl substituted of which at least 50 percent are dimethylhexanoic acids and which acids are not more than 25 percent ethyl substituted and .contain less than about 0.3 percent of 2-ethylhexanoic acids, said isomeric branched chain octanoic acids being further characterized by having not more than seven and not less than five carbon atoms in a straight chain.

In the preferred method of drying the basic aluminum octanoate soap containing sorbed oil, the precipitated soap is dehydrated until the moisture content is between about 1.0 percent and 3.0 percent, for example about 1.5 per cent. This is accomplished by heating the soap in an oven at about 140150 F., for 10 to 18 hours. The soap is then pre-ground to particle size of about 4 mesh and is mixed with about 1 to 5 percent by weight of an inert powder such as a silica aerogel as a separating agent to facilitate final comminution and to reduce the tendency of the final powdered soap to pack. The soap is then reduced to powder form by grinding or other comminuting means after which it is heated for several hours at about 212 F., to reduce the moisture content tothe range of 0.2 to about 0.5 weight percent.

The oil presolvated soaps prepared according to the above procedure produce stable gels which in general are insensitive to atmospheric moisture. As indicated in Tables 3 to 7 inclusive, the moisture sensitivity of the soaps was determined. This was accomplished by subjecting the dehydrated soaps to atmospheric conditions of 80 percent relative humidity at 80 F. In this test, the soap, dispersed in thin layers, is subjected to the humid atmosphere for a period of one quarter hour. Such exposure increases the moisture content of the presolvated soap and in general increases the rate of curing of the gels produced from the soap without effecting substantially the stability of the hydrocarbon gels. The characteristic property of accelerating the curing rate without deleterious effect on the stability of the hydrocarbon gel is not common to con ventional aluminum soap gelling agents. Thus Napalm is adversely affected by exposure to a highly humid atmos-' phere, hydrocarbon gels produced from Napalm, so ex posed, producing much less stable gels'than non-exposed Napalm.

In determining the moisture content of the aluminum soap the benzene azeotrope method is used, that is, essentially the A. S. T. M. Method D-46 except that a one-liter flask heated by an electrical heating mantle and containing 500 ml. of benzene solvent is used.

The preparation of the sodium isooctanoate is described below and the preparation of a representative basic aluminum issoctanoate oil-containing soap gelling agent and the preparation of oil-containing basic aluminum Z-ethylhexanoate soap gelling agent according to my invention are described in Examples I and II respectively.

SODIUM ISOOCTANOATE SOLUTION A solution of 74.0 weight percent of rayon grade sodium was preheated and pumped at an average rate of 4.5 pounds per hour into the bottom of a cylindrical re action vessel at about 685 F. The reactor was fitted 23 5.1 ,aeo

7 with .a stirrer and .bafiies to provide agitation. Oxo process isooc'tyl alcohol (B. P. 181 -C.-1'92.5 (1., N 1.4305, Sp. Gr. 0.833) preheated to about 685 F. was pumped into the bottom of the reactor through a seperate inlet-at an average rate of 9.3 pounds per hour, reactor temperature being maintained at about 720 F. Oxidation of the alcohol took place with evolution of hydrogen at the rate of about 55 cubic feet per hour. This gas was vented at such a rate as to maintain a pressure o'f'about 210 p. s. i. g. on the reactor and solution vessel. The sodium isooctanoate, excess sodium hydroxide, and trace of unreacted alcohol passed through an overflow line at the top of the reactor into asolution vessel held at a temperature of about 410 P. where water was added at the 'rate of about 29 pounds per hour to dissolve the soap and excess caustic. Unreacted alcohol was flashed off with steam from the top of the solution vessel to a separator where it was recovered at a rate of about 0.3 pound per hour. Over a twenty-one hour period, 194.8 pounds of the isooctyl alcohol was fed to the reactor and there was recovered sodium isooctanoate soap equivalent to 187.9 pounds of isooctyl alcohol corresponding to a yield of 96.2 percent, along with 6.9 pounds of unconverted isooctyl alcohol. An aqueous soap solution was withdrawn from the bottom of the solution vessel and cooled. This solution had an average analysis corresponding to the following:

Weight percen EXAMPLE I.-OIL-CONTAINING BASIC ALUMINUM ISOOCTANOATE SOAP To .3380 parts by weight of water in a precipitation vessel was added 17.6 parts by weight of NaOH. To this alkali solution was added 1460 parts by weight of sodium isooctanoate solution containing 462 parts by weight of sodium isooctanoate and 149 parts by weight of free NaOH. There was then added slowly, with agitation of the sodium isooctanoate solution, 60 parts of a medicinal heavy grade petroleum white oil having a viscosity of 360 seconds at 100 F. (Saybolt Universal) corresponding to percent of oil'based on the isooctanoic acid .in the solution. Stirring of the solution was continued until the oil was completely emulsified to give a creamy uniform emulsion. While agitating this emulsion 845 parts by weight of 32 B. aluminum chloride solution dissolved in 1220 parts by weight of water was added. The pH of the basic sodium isooctanoate solution before aluminum chloride addition was about 14. Precipitation started at a pH of about 9.5. The final pH was about 3.5 at which point there remained no emulsified oil in the supernatent liquid. The precipitated basic aluminum isooctanoate containing sorbed oil was filtered, washed free of chloride, rough ground and dried for about 18 hours at about 150 F. to a moisture content of 0.7 percent. The partially dried soap was then thoroughly mixed with 5 percent (by weight) of a silica aerogel (Santocel) and reground to a powder of a fineness corresponding to about 75 percent passing a 100 mesh screen and the comminuted product was then heated forabout three hours at '2l0212 F. The oil-containing basic aluminum isooctanoate soaps used in obtaining the results given in Tables 4, 5, and 6 below were prepared according to the above procedure, using the appropriate amount of oil in the emulsification step to give the indicated sorbed .oil content in the specific soaps. The soaps described in Table 3 (oil content zero) were prepared :in like manner except :that :no oil emulsified in the basic sodium isooctanoate solution.

To 2000 grams of water was added 82 grams of NaOH and 201) grams of 2-ethylhexanoic acid. The mixture was stirred to obtain complete solution of the 2-ethylhexanoic acid and then 40 grams of petroleum medicinal white oil (of the same grade as used in Example I) was emulsified in the basic aqueous solution of sodium 2-ethylhexanoate. 'The solution before oil addition had -a pH of 12+. To the emulsion was added slowly, .a mixture of 330 ml. of AlC13 solution (32 B.) in .370 grams of water. The pH dropped to about 3.5 during the precipitation of the basic aluminum Z-ethylhexanoate containing the sorbed oil, i. e., about 20.percent oil .by weight, based on the 2-ethylhexanoic acid. The .precipitate was filtered and washed free of inorganic salt and dried for fifteen hours at 150 F. after which it was ground to a powder corresponding to about '75 percent passing through a mesh screen. It was then dried for an additional six hours at about F. This soap was used to obtain the data given for oil-containing basic aluminum 2-ethylhexanoate in Table 7. Data given in Table 7 for oil-free basic aluminum Z-ethylhexanoate soap were obtained from 2-ethylhexanoate soap prepared in like manner except that oil was not emulsified in the aqueous solution of basic aluminum Z-ethylhexanoate.

'In using the gelling agents produced according to the foregoing procedures, a quantity of the agent is added to the hydrocarbon fuel and stirred at ambient temperature. Between about 0:5 and about 6.0 weight percent, preferably between about 1.0 and 4.0 weight percent of the precipitated basic aluminum .octanoates, the octanoate radicals of which consist essentially of branched chain isooctanoate radicals and/or 2-ethylhexanoate radicals produce, with the sorbed oil, the superior gels. The novel gelling agents are particularly etfective when used at relatively low concentrations, that is, about 1.5 weight percent to about .5 weight percent in gelling gasolines, kerosenes, diesel fuels, jet fuels, and the like to relatively high gel viscosity in a shorter period of time than oil-free soaps and the gels mature more rapidly than gels produced with oil-free soaps.

Gelation begins immediately when the agent and liquid are stirred at ambient temperatures. The extent of initial gelation is a measure of the gelling properties and is determined by a standard test described hereinafter as the Vortex Time, that is, the time necessary to obtain a specific diminution of the amplitude of a vertex in a mass stirred under defined conditions. This Vortex Time is a measure of the rate at which -.a gelling agent causes a hydrocarbon solvent to thicken. vA Vortex Time ofabout 10 minutesor .less,.in the :productionof gels having the higher consistency range described hereinbelow, is desired. This is realized with my improved .gelation agent at the 4 percent concentration level. Even at lower concentrations of my improved gelling agent which give Gardner Load values in the lower viscosity range described below, Vortex Times lower than 10 are possible.

For general laboratory testing of gelling agents a quantity ofthe hydrocarbon solvent is introduced into a squaretype pint Mason jar having dimensions approximately 3 inches by 3 inches by 5 inches deep. A total weight of 200 grams of solvent and gelling agent is employed. For

example, if 4 'weightpercent gel is to be prepared, 8 grams of the gelling agent will be added to 192 grams of the solvent.

A glass stirring rod is employed which is about inch in diameter with four vanes, by by Ms inch, set at .right angles and having faces parallel to the axis of the rod. The stirrer is mounted within the jar with the bottom of the stirrer 1/2 inch above the bottom of the jar. A ref erence mark is made on the glass rodone centimeter below the surface of the testsolvent.

The stirring speed is adjusted to 300:: R. P. M. and the temperature of the solution is controlled at some standardized temperature. Examples shown below in Tables 3 to 7 inclusive were carried out at 77 F. and 35 F. The time elapsed between addition of the gelling agent sample and immersion of the reference mark by the rising vortex is recorded as the Vortex Time. The gel continues to cure for from 6 hours to about a day without stirring after the initial gelation occurs, as measured by the Votex Time.

,Theproperties of the final gel are measured by the fGardner Load, which is ameasure of the viscosity and indicates theconsistency and when the Gardner Load values are determined at time intervals following initial gelation thevaluesobtained indicate the stability of the cured hydrocarbon gel with respect to consistency. It is determined in a Gardner Mobilometer, an apparatus described-1n Physical and Chemical Examination. of Paints, 'Va'rnishes, Lacquers and Colors, 10th edition (May 1946) by Henry A. Gardner and G. G. Sward, distributed by Henry A. Gardner Laboratory, Inc., Bethesda, Maryland. The test is ordinarily made at 24 or 48 hours after initial gelling has taken place and the values are in terms of grams per 100 seconds. In general, a Gardner Load in the range of about 100 to about 225 grams designates a desirable "consistency for portable flame thrower service whereas a load of about 350 to about 650 grams indicates a suitable consistency for other military incendiary purposes. Ordinarily the load should remain below about 650 grams if the gel is to have the desired splattering, cohesion and burning properties. My improved oil-containing basic aluminum octanoate gelling agent produces, with gasolines, a product which is a stringy material having high splattering and good cohesion and burning properties when dispersed by flamethrower apparatus.

The instrument used in the Gardner tests consists essentially of a cylinder supported on a base plate, a plunger or piston, and a collar to support the plunger. The cylinder is 8.0 inches deep and 1.538 inches in diameter. The plunger consists of a disc 1.500 inches in diameter with four perforations 0.250 inch in diameter and a weight pan or holder supported by the upper end of a tube or rod fixed at its lower end to the disc. The weight of the moving system which includes the disc, connecting rod or tube, and the Weight support is 100 grams.

To make the test, the cylinder is filled to a depth of 20 centimeters with the gel to be tested and is leveled by means of adjustingscrews. The disc end of the plunger is then introduced into the cylinder with the connecting Gelling .propertiesof basic alum:

- corresponding oil-free basic aluminum octanoates in Tables 3 to 7 inclusive hereinbelow. The formulation of the standard test solvent used in evaluating the gelling agents conforms to Military Standard M8602 (October 22, 1951) and has the following composition:

- Weight per cent N-heptane 57 Benzene 18 Cyclohexane 20 Isooctane 5 TABLE 3 I v I Gelling properties of basic aluminum isooctantoate .soapl containing no sorbed oil Evaluation 1 2 3 4 5 6 Exposure to Moist Air, hrs 0 0. 25 0 0. 25 0 0.25 Moisture in Final Soap, wt.

Percent 0. 4 1. 3 0. 4 1. 3 0. 4 1. 4 Wt. Percent Soap in Gel 1. 5 1. 5 2. 0 2.0 4. 0 4. 0 At 77 F.:

Vortex Time, min t- 40 75 28 2. 4 3. 1 Gardner Load, g./ se

at 24 hrs 150 225 210 620 515 1 Humidity test consists of submitting soup to relative humidity of 80 percent at 80 F. for a period 004 hr. 1 The basic aluminum isooctanoate gelling-agent used for experiments 1 to 6 inclusive in Table 3 contained no sorbed oil. The gels described in Table 3 are typical laboratory-prepared gels produced by oil-free isooctanoate gelling agent, that is, gelling agents having relatively low gelling rates at soap concentrations of 2 percent or less. The gelling rates of the non-presolvated soaps may also be improved by heat treatment as taught and claimed in copending application, Serial No. 339,504, filed March 2, 1953, entitled Rapid Gelling Basic Aluminum Soaps.

In Table 4 below are shown the gelling rates 10f basic aluminum isooctanoate soap containing different amounts of sorbed medicinal grade heavy white oil. This oil had a viscosity of about 350 seconds at 100 F. (Saybolt Universal). Viscosity-time performance of the hydrocarbon gels prepared .fromsynthetic gasoline (standard test solvent) is also included in the table.

TABLE 4 num isooctanoate soap containing sorbed white oil Evaluation 7 8 9 10 11 12 13 14 15 16 17 18 Wt. Percent 011 in Soap 0 2. 0 5. 0 5. 0 10. 0 10.0 10. 0 10.0 15.0 15.0 15. 0 15.0 Exposure to Moist Air, hrs 0 0. 25 0 0. 25 0 0. 25 0 0. 25 0 0. 25 0 0. 25 Moisture in Final Soap, wt. Percent 4 1. 4 0. 6 1. 4 0. 3 1. 4 0. 3 1. 4 0.3 1. 4 O. 3 1. 4, fisrz ent Soap in Ge] 2. 0 2. 0 2.0 2. 0 2.0 2.0 4. 0 4.0 2.0 2. 0 4. 0 4. 0 Vortex Time, min 71 22 41 19 5. 5 7. 0 1. 7 2. 4 3. 1 4. l 1. 3 1. 8 Gardner Lead, g /100 sec.-

- at 24 hrs 200 240 210 295 225 705 545 280 220 685 540 220 205 265 210 705 540 265 200 600 505 tube aligned by a collar. marks 10 centimeters apart on the stem of the plunger to pass through the collar is then recorded. The pair of marks are located so that they pass through the collar of the bracket as thedisc passes through the mid portion of'the cylinder. Thus theplunger is in motion both at the beginning and at the end of the test interval. In re-' porting results, the Gardner Load is determined by The time required for two of soap used re'' .11 tion of gelling agent are realized with increasing amounts of. sorbed oil.

In Table is shown the performance of aluminum isooctanoate gelling agent having sorbed therewith two difierent oils of approximately the same viscosity range,

TABLE 7 Gelling performance of basic aluminum Z-ethylhexmwate I soap with and without sorbed white oil Evaluation 1 43 i 44 l l 46 i 47 48 49 v Wt. Percent Oil in Soap 20 20 20 20 0 0 0 0 Exposure to Moist Air, hrs 0 0. 25 O 0.25 0 0.25 0 0. 25 Wt. Percent Soap in Gel 1. 7 1. 7 3. 3 3.3 2 2 4 4 At 77 FL:

Vortex Time, min 27 29 1. 2 1.6 78 62 5. 8 5. 3

Gardner Load, g./100 scc.-

at 24 hrs 100 355 425 350 345 at 168 hrs "a 255 245 460 520 215 195 515 510' the blended oil being a non-extracted oil and the other 20 oil-free basic aluminum Z-ethylhexanoate soap is made Gelling performance of aluminum isooctanoute soap containing 12.5% sorbed heavy oils I High Flash Blended Petroleum Oil 1 SAE 20 (Solvent Extracted) Evaluation l i 1 Exposure to Moist Air, hrs 0 i 0.25. .0 0.25 0 0.25 0 0.25 0 0.25 0 0.25 Moisture in Final Soap, Vt. Perce 0. 4 i 1. 4 0. 4 i l. 4 0. 4 1. 4 0. 2 1. 2 0. 2 1. 2 0. 2 1. 2 Wt. lgecent Soap in Gel 1. 4 1. 4 1.8 1.8 3. 6 3. 6 1. 4 1. 4 1.8 1.8 3.6 3. 6 At 77 n:

Vortex Time, min i 9. 0 1,1 7.0 I 7.1 2.1 2. 4 11 21 l 7.8 15 2. 2 2. 4 Gardner Load, g./l00 see.

at 24 hrs i 175 205 175 555 455 205 160 240 190 620 465 at 48 hrs. 120 190 465 390 145 225- 180 540 450 at 168 hrs E 110 160 450 370 175 150 215 170 560 410 l Viscosity at 100 F., 300 (S.S.U.)

Referring to Table 5 above, it is seen that basic aluminum isooctanoate soaps containing 12.5 percent by weight of sorbed, relatively high boiling hydrocarbon oils are quite effective at low soap concentrations for increasing the rate of gelation and in the production of relatively stable gels at these low concentrations. The data indicate that it is not necessary to use, as sorbtion oils in my improved gelling agent, highly refined oils such as white oils or solvent extracted oils but that oils which have not undergone acid treatment or solvent extraction are suitable.

The performance of aluminum isooctanoate gelling agent containing sorbed, solvent extracted lubricating oils. of S. A. E. 10 and S. A. E. 50 grade is shown in Tabe 6.

TABLE 6 40 with such soap containing 20 weight percent of heavy grade medicinal white oil (described above). Although the effect of the sorbed oil in regard to gelation properties is less marked with basic aluminum Z-ethylhexanoate soap than is the case with oil-sorbed aluminum isooctanoate soap, there is a marked increase in gelation rate, that is, approximately a fourfold 4 percent soap concentration level.

The above data indicate that my improved basic aluminum octanoate soaps containing sorbed oil to the extent of from about 2.0 weight percent to about 25 weight percent based on the octanoic acid equivalent of the octane ate content of said soap are effective in increasing-the gelling rate and in the production of rapid curing of stable- Gelling performance of uluminum -isooctanoate soap containing sorbed lubricating oils S. A. E. 10 (Solvent lilxtracted), 8. A. E. 50 (Solvent Extracted) Evaluation p Vit, percent Oil in Soap 20 20 20 20 20 20 12. 5 12. 5 12. 5 12.5 12. 5 12. 5 Exposure to Moist Atmosphere, hrs.-. 0 0.25 0 0.25 0 0.25 0 0.25 0 0.25 0 0.25 Moisture in Final Soap 0.4 1.0 0. 4 1, 0 0.4 1.0 0.3 1.1 d. 3 1. 1 0. 3 1. 1 7E enicent Soap in Gel 1.5 1.5 2.0 210 4.0 4. 0 1.4- r 1. 4 1.8 1. 8' 3. 6 3. 6 Y 7 .1.

Vortex Time, min 8.2 14 5.9 11 215 33 32 26 16 Y 18 '0.9' 1.5 Gardner Load, g./100 sec. g

at 24 hrs 195 265 220 600 495 165 170 230 205 570 520 at 48'hrs. 185- ,175 245 215 600 520 185 160 230 195 550 490 at 168 hrs. 155 160 240 220 580 500 165 145 215 505 480 Viscosity 165 seconds at 100 F. (Saybolt Universal).

1 Viscosity 1462 seconds at 100 F. (Saybolt Universal).

"The performance data indicate that a hydrocarbon oil as viscous as S. A. E. 50 grade. when sorbed by isooctanoate soap is effective in reducing the vortex time and progels of liquid hydrocarbons when the presolva'ted soap is used in a concentration of from about 0.5 percent to about 6 percent in said hydrocrabon oils.

In Table 7, a comparison of the gelling properties o t increase in the rate at the I claim:

1. The method of making an agent for gelling a hydrocarbon boiling in the range of about 100 to 600 R, which method comprises intimately mixing an inorganic, water-soluble, aluminum salt with a dilute aqueous solution of alkali metal branched chain octanoate and alkali metal hydroxide in the presence of a heavy hydrocarbon oil having a Saybolt Universal viscosity in the range of about 100 to 1500 seconds at 100 F. and being of higher boiling range than the hydrocarbon to be gelled, the amount of said heavy hydrocarbon oil being in the range of about 2 to 25 per cent by weight based on the octanoic acid equivalent of the alkali metal branched chain octanoate in said solution, said heavy hydrocarbon oil being emulsified in aqueous solution during said mixing and sorbed in the water-insoluble basic aluminum branched chain octanoate which is precipitated during said mixing the branches on the branched chain octanoate radicals being selected from the class consisting of methyl and ethyl, washing the precipitated basic aluminum branched chain octanoate soap to free the precipitate of alkali metal and inorganic salt, drying said precipitate to a moisture content of not more than 3 per cent, and grinding the dried basic aluminum branched chain octanoate with the heavy oil sorbed therein.

2. The method of claim 1 wherein the heavy hydrocarbon oil is a white oil.

3. The method of claim 1 wherein the heavy hydrocarbon oil is emulsified in an aqueous solution of sodium branched chain isooctanoate soap and an aqueous aluminum chloride solution is added thereto during the mixing step.

4. The method of claim 1 which includes the step of 14 mixing about 1 to 5 per cent of a silica aerogel with the oil-sorbed basic aluminum branched chain octanoate prior to a final grinding step.

5. The method of claim 4 which includes the step of heating the oil-sorbed basic aluminum branched chain octanoate after the final grinding step to reduce its moisture content to a range of about .02 to .5 weight per cent.

6. The method of. claim 1 wherein the alkali metal branched chain octanoate is sodium isooctanoate.

7. The method of claim 1 wherein the alkali metal branched chain octanoate is sodium 2-ethyl hexanoate.

8. The method of claim 1 wherein the alkali metal branched chain octanoate is a mixture of about 10 to 60 weight per cent of sodium 2-ethyl hexanoate and 90 to 40 weight per cent of sodium isooctanoate.

9. The method of claim 1 wherein the amount of heavy hydrocarbon oil is in the range of about 5 to 20 per cent by weight based on octanoic acid equivalent of the alkali metal branched chain octanoate.

10. The method of claim 1 wherein the inorganic water-soluble aluminum salt is aluminum chloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,390,609 Minich Dec. 11, 1945 2,417,071 Gebhart et al. Mar. 11, 1947 2,582,833 Hunn Jan. 15, 1952 2,584,041 Nowak et al. Jan. 29, 1952 2,618,536 Hunn Nov. 18, 1952 2,628,202 Allison et al. Feb. 10, 1953 2,626,897 Young et al. Jan. 27, 1953 

1. THE METHOD OF MAKING AN AGENT FOR GELLING A HYDROCARBON BOILING IN THE RANGE OF ABOUT 100 TO 600* F., WHICH METHOD COMPRISES INTIMATELY MIXING AN INORGANIC, WATER-SOLUBLE, ALUMINUM SALT WITH A DILUTE AQUEOUS SOLUTION OF ALKALI METAL BRANCHED CHAIN OCTANOATE AND ALKALI METAL HYDROXIDE IN THE PRESENCE OF A HEAVY HYDROCARBON OIL HAVING A SAYBOLT UNIVERSITY VISCOSITY IN THE RANGE OF ABOUT 100 TO 1500 SECONDS AT 100* F. AND BEING OF HIGHER BOILING RANGE THAN THE HYDROCARBON TO BE GELLED, THE AMOUNT OF SAID HEAVY HYDROCARBON OIL BEING IN THE RANGE OF ABOUT 2 TO 25 PER CENT BY WEIGHT BASED ON THE OCTANOIC ACID EQUIVALENT OF THE ALKALI METAL BRANCHED CHAIN OCTANOATE IN SAID SOLUTION, SAID HEAVY HYDROCARBON OIL BEING EMULSIFIED IN AQUEOUS SOLUTION DURING SAID MIXING AND SORBED IN THE WATER-INSOLUBLE BASIC ALUMINUM BRANCHED CHAIN OCTANOATE WHICH IS PRECIPITATED DURING SAID MIXING THE BRANCHES ON THE BRANCHED CHAIN OCTANOATE RADICALS BEING SELECTED FROM THE CLASS CONSISTING OF METHYL AND ETHYL, WASHING THE PRECIPITATED BASIC ALUMINUM BRANCHED CHAIN OCTANOATE SOAP TO FREE THE PRECIPITATE OF ALKALI METAL AND INORGANIC SALT, DRYING SAID PRECIPITATE TO A MOISTURE CONTENT OF NOT MORE THAN 3 PER CENT, AND GRINDING THE DRIED BASIC ALUMINUM BRANCHED CHAIN OCTANOATE WITH THE HEAVY OIL SORBED THEREIN. 